A quality assurance program for ancillary high technology devices on a dual-energy accelerator

Our facility has added high-technology ancillary devices to our dual-energy linear accelerator. After commissioning and acceptance testing of dual asymmetric jaws,dynamic wedge, portal imaging, and multileaf collimation (MLC), quality assurance programs were instituted. The programs were designed to be both periodic and patient specific when required. In addition, when dosimetric aspects were affected by these technologies, additional quality assurance checks were added. Positional accuracy checks (light and radiation) are done for both asymmetric jaws and MLC. Each patient MLC field is checked against the original simulation or digitally reconstructed radiographs. Off;axis Factors and output checks are performed for asymmetric fields. Dynamic wedge transmission factors and profiles are checked periodically, and a patient diode check is performed for every new dynamic wedge portal. On-line imaging checks encompass safety checks along with periodic measurement of contrast and spatial resolution. The most important quality assurance activity is the annual review of proper operation and procedures For each device. Our programs have been successful in avoiding patient-related errors or device malfunctions. The programs are a team effort involving physicists, maintenance engineers, and therapists.